RUN far, far away from the dealership and fast! I had this expeience with my XJR, took it to Jaguar and they wanted me to spend big money and replace nearly everything. Turned out to be a $0.20 part vs the $14,000+ they wanted me to spend.

Take it to someone that can properly diagnose your vehicle. To me it sounds like it would be more a leaky air shock than the suspension module which seems to be working otherwise...